JPS61105748A - Thermal magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To provide a magnetic field necessary for magnetic field inversion without a driving device of a magnetic field generating equipment by extending the magnetic field generating equipment mounted opposite a laser beam irradiating device which heats a magnetic film partially, though the total length of a magnetizable area of a recording medium. CONSTITUTION:The laser beam of a beam source 4 focuses on a magnetic thin film of a recoding medium, heats the medium partially, reduces its magnetic resistance, and the magnetic flux of a coil 10 generated in response to a recoding signal magnetizes the heated area to record specified information. A magnetic field generating equipment 11 is extended through the total length of a magnetizable area of the recording medium, and the magnetic flux from a very thin ferromagnetic material 14 of 1mu thickness is superimposed perpendicularly to the flux from the coil 10. Hence the magnetic field generating equipment 11 does not necessitate a driving device to move over the medium although a magnetic field necessary for magnetic field inversion is securely imposed to the medium as a base 1 is rotated with a motor 3.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a thermomagnetic recording and reproducing apparatus for recording and reproducing information on a magnetic medium having perpendicular anisotropy by heating with a laser spot or the like.

[Prior Art] Conventionally, as this type of thermomagnetic recording/reproducing means, for example, Mn3
i is used as a recording medium, and by utilizing the temperature dependence of the coercive force of the thin film, a light beam such as a laser beam is irradiated, and the heat from the spot causes magnetization reversal to record information, and information is recorded without causing magnetization reversal during reproduction. There is a device in which a laser beam spot of a certain extent is illuminated on the recording area and information is read out by the Kerr (l(err) effect).

In other words, if we describe this method in more detail), it is 1.
A magnetic thin film such as vjnBi or rare earth amorphous alloy is formed on the base by vapor deposition or sputtering, and a bias magnetic field is applied to the thin film so as to magnetize it in a certain direction perpendicular to the film surface. Then, the laser beam emitted from the light source is modulated with a recording signal, and is irradiated onto the recording medium as a slit through an objective lens to increase the temperature of the irradiated area, thereby reducing the coercive force of the medium. When the magnetic field becomes smaller than the bias magnetic field, information is recorded by magnetic reversal.

Another method is to focus a laser beam on the medium and locally heat the medium to lower the coercive force, and in this state magnetize the medium with a magnetic field that changes according to the recording signal to perform recording. be.

In all of these means, the medium is locally heated by the energy of the laser beam to lower the coercive force at the spot, and the magnetic field acting thereon performs thermomagnetic writing.

JP-A-51-97413 specifically discloses the thermomagnetic recording and reproducing apparatus described above. The technology disclosed in this prior art is a device for reversing the magnetization of a recording medium, which applies a magnetic field generated in an air gap to the recording medium by passing current through U-shaped magnetic cores arranged to sandwich the recording medium. It is.

[Problems to be Solved by the Invention] According to the above-mentioned conventional technology, the magnetic core of the magnetic field generating device is iron-shaped, which increases the weight and complicates the device for driving the recording medium in the radial direction. There was a problem that the drive length became long. Further, the air gap length of the U-shaped magnetic core is required to be about 5 mm, taking into account the amount of deflection of the recording medium. Even if current is passed through the magnetic core with this air gap length, the magnetic field required for magnetic field reversal cannot be applied to the recording medium.

In order to solve the above-mentioned problems, this invention provides a magnetic field generator fixed on one surface of the recording medium in the radial direction of the recording medium, thereby making it possible to reliably apply the magnetic field necessary for magnetic field reversal to the recording medium. The present invention aims to eliminate the need for a drive device for a magnetic field generating device.

[Means for Solving the Problems] The device of the present invention heats a magnetic field generating device fixedly provided on one surface of a recording medium so that it extends over the entire length of the magnetizable range of the recording medium. Recording and reproduction are now possible simply by moving the means for irradiating laser light.

[First Embodiment] An embodiment of the present invention will be described below with reference to the drawings. Second
The figure shows an example in which the present invention is applied to recording by magnetizing a medium using a magnetic field that changes according to a recording signal. In the figure, 1 is a disc-shaped base, and this base 1
A magnetic material 112 such as Mn3i is deposited thereon by vapor deposition or sputtering to form a recording medium. Further, the base 1 is held horizontally and rotated by a motor 3 at a predetermined speed.

On the other hand, 4 is a light source that generates a laser beam. The laser beam from this light source 4 is applied to a half mirror 6 via a light modulator 5 and a polarizer 51, and reflected there. I try to give it on two sides. In this case, the laser beam is focused on two surfaces of the thin film. Also,
An analyzer 8 and a photoelectric conversion element 9 are disposed on an extension of the optical axis passing through the lens 7 via the half mirror. These analyzer 8 and photoelectric conversion element 9 are connected to magnetic thin film 2 during reproduction.
Laser light reflected from a surface is detected using the Kerr effect.

A first magnetic field generator, for example a coil 10, is provided above the magnetic thin film 2. This carp 5
7%/1 The magnetic field 10 generates a magnetic field that changes according to a recording signal, for example, a digital signal, and the magnetic flux generated by this is applied to the thin 11SI2 portion heated by the laser beam.

A second magnetic field generator 11 is provided opposite the coil 10 with the base 1 in between. This magnetic field generator 11
The magnetic flux is superimposed on the magnetic flux of the coil 10 to invert the magnetic field, and is placed close to the portion of the magnetic thin film 2 where the laser beam is focused. Further, this second magnetic field generating device 11 is made long in the radial direction of the base 1, so that the ferromagnetic portion of this magnetic field generating device @11 extends over the entire length of the magnetizable range.

This eliminates the need to move the magnetic field generator 11.

In this case, the second magnetic field generating device 11 is made by bonding a ferromagnetic material 13 such as ferrite to a non-magnetic material 121 such as ceramic as shown in FIG. A ferromagnetic material 14 having a relatively high saturation magnetic flux density such as Permalol or Sendust is deposited by sputtering or the like, and another non-magnetic material 122 whose abutting surfaces have been polished in advance is butt-joined, and then an R end surface is formed. It is obtained by doing.

In this configuration, the rotation of the base 1 moves the focal position A of the laser beam and the second magnetic field generator 11 in the direction B shown in the figure, that is, in the radial direction of the base 10, as shown in FIG. A spiral magnetization track C is drawn on the surface.

Next, its effect will be explained. In this case, such an embodiment will be described in which the magnetic field is changed in response to a recording signal, and the medium is magnetized by this magnetic field to perform recording. Therefore, it is assumed here that no modulation operation is performed in the optical modulation device 5.

In this way, when a laser beam is generated from the light source 4, the laser beam is transmitted to the optical modulator 5 (no modulation operation is performed).
, is applied to the half mirror 6 via the polarizer 51, reflected there, and applied to the magnetic thin film 2 via the lens 7. When the laser beam is focused on the thin film 2, the spora 1 to 1 are locally heated and the resistance is reduced.

When a magnetic field is generated from the coil 10 in accordance with the recording signal in this state, the resulting magnetic flux magnetizes the portion of the thin film 2 heated by the spot, thereby recording predetermined information. In this case, the magnetic flux generated by the coil 10 is superimposed on the magnetic flux from the extremely narrow (approximately 1 μm) ferromagnetic material 14 portion of the second magnetic field generating device 11, and is applied to the heated portion of the thin film 2 in the perpendicular direction. Therefore, the magnetic flux from the second magnetic field generating device 11 is superimposed on the magnetic flux of the first signal magnetic field generating device, and the magnetic field necessary for magnetic field reversal can be easily obtained.

Note that the second magnetic field generating device may also generate magnetic flux based on the information signal in the same manner as the first signal magnetic field generating device. Furthermore, it is possible for the first magnetic field generating device to perform the intended purpose of recording and reproducing.

Thereby, information is recorded at high density along the magnetized track C as shown in FIG. 4 by rotating the base 1 by the motor 3 in the same manner.

Therefore, with such a configuration, the recording density on the recording medium can be dramatically increased, so that information can be recorded extremely efficiently.

It should be noted that the present invention is not limited to the above-mentioned embodiments, but can be implemented with appropriate modifications within the scope without changing the gist. For example, in the above description, recording is performed by magnetizing the medium using a magnetic field that changes according to a recording signal. However, a magnetic field generator, that is, a coil 10, is used to set a constant magnetic field as a bias magnetic field, and a laser beam is transmitted to an optical modulator 5. It can also be applied to a system in which recording and reproduction are performed by modulating a recording signal. Furthermore, although a disk-shaped medium is used in the above description, a drum-shaped or flat medium may also be used.

As mentioned above, according to the present invention, the second magnetic field generating device is provided so as to extend over the entire length of the magnetizable range of the recording medium, so that the magnetic field generating device can be driven in accordance with the movement of the laser beam. It is possible to provide a thermomagnetic recording and reproducing device that can be omitted.

[Brief explanation of drawings]

Fig. 1 is a diagram for explaining the temperature distribution of a laser beam spot, Fig. 2 is a schematic configuration diagram showing an embodiment of the present invention, Fig. 3 is a perspective view of an auxiliary magnetic pole used in the embodiment, and Fig. 4 is a diagram for explaining the temperature distribution of a laser beam spot. The figure is a diagram for explaining the same embodiment. 1...Base 2...I film 3, 12...Motor 4-light source 5...Light modulator 6...Half mirror 7...Lens 8...Analyzer 9...Light Conversion element 10... Coil (first signal magnetic field generator) 11... Second magnetic field generator Fig. 2 Fig. 3 Fig. 4

Claims (1)

[Claims] In a thermomagnetic recording and reproducing apparatus, a magnetic field generating device is provided at a position sandwiching the medium opposite to a laser beam irradiation means that locally heats the magnetic film of the recording medium, in which a laser beam that locally heats the magnetic film of the recording medium is provided. A thermomagnetic recording and reproducing device characterized in that a magnetic field generating device provided opposite to a means for irradiating light is provided so as to extend over the entire length of a magnetizable range of a recording medium.